In rolling of a flat strip, the relative velocity of strip with respect to the roller is

The true stress at fracture of a tensile tested specimen, having an initial diameter of specimen at fracture is $$10$$ $$mm,$$ then the engineering stress, in $$MPa,$$ at fracture is ____________

A surface is prepared specially for an application with the profile as shown in the figure.

The theoretical $${R_a}$$ value for this surface, in $$\mu m,$$ is _______________.

During the measurement of internal taper of a part using standard balls of diameter $$15$$ $$mm$$ and $$20$$ $$mm$$, the large ball is found to protrude by $$5$$ $$mm$$ $$\left( {{h_1}} \right)$$ and the top of small ball is found to be $$35$$ $$mm$$ $$\left( {{h_2}} \right)$$ below the top face of the gauge. The taper angle, in degree, is ________________.